| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent overlapping printing to an already used face of paper in an image forming apparatus such as a printer. <P>SOLUTION: An image data is inputted by picking up one face of the paper by an imaging means 102. A frequency conversion part 104 carries out, for example, a two dimentional wavelet conversion to the image data. An absolute value sum is calculated of coefficients for every sub band of LH, HL and HH outputted by the frequency conversion part 104 and when the absolute value sum of the coefficients for the sub bands exceeds a prescribed value, the paper face picked up by the imaging means 102 is determined to be a used face and when the value is not exceeded, determined as an unused face. The discrimination between the used face and the unused face can also be carried out with good precision for paper that is other than white paper such as colored paper or straw paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
